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The Lowdown on Lidar (docs.google.com)
667 points by timdierks on July 31, 2014 | hide | past | web | favorite | 271 comments

I confess I was expecting to not care for this. I'm not sure how any of it should be surprising, as it seemed fairly straight forward analysis of the tools.

That said, this was a ridiculously fun read. More detailed than expected for some parts, and always informative. I'm glad it did not come across as anti speed detectors. Really more of a "know the limitations."

I hope he realizes this, as much as I hope everybody else realizes this, that the only reason why he got the violation reduced was because he brought his attorney on board. Anybody who lives in California whose contested a ticket knows that 9/10 times (if not even more than that) judges side with the officers -- whether they have a strong case or not -- the State of California certainly doesn't want it's residents to get any ideas.. if you know what I mean.

I wonder if his attorney cost more than the actual citation? Most people can't afford lawyer fees, so cops in California get away with this small stuff all the time without any fuss, whether they were liable or not. Congrats Joshua Block -- BTW I loved "Effective Java"!

I'm surprised they exonerated him, considering his driving history...

Turns out he apparently blew a red light with his Boxster in 2010 and hit another car:


That's a strange story. According to the blogger's version og the incident, he was struck an injured by someone clearly breaking the law. Why wasn't the other driver detained by police and arrested?

I managed to win 3 tickets in CA (over a period of about 9 years) using trial by written declaration. In fact one of them was using a very similar argument to OPs. It's a bunch of work as I painstakingly assembled my case with loads of supporting evidence but I think it's important to stand up for yourself.

Admittedly all 3 cases were dismissed because the officer didn't bother to write a response but TBWD is a lot cheaper than lawyering up and does sometimes work.

What if there was an online tool to help you assemble your case? Do you think more people would fight tickets?

There's more than just the citation cost, though. A ticket that involves points will come with a corresponding insurance premium increase for at least a few years.

> I wonder if his attorney cost more than the actual citation?

Doesn't really matter -- getting a[nother] point on your license can be more costly log-term (insurance rates, having to re-take drivers test, etc).

Often (but not always) in the UK, the laser is accompanied by video footage which shows where the beam has been trained and it is a combination of both the video and laser reading (shows on the video) which is the evidence. (all tripod mounted - so I suspect many of the issues detailed are well known). Sounds like that would give good supporting evidence for a challenge.

However, traffic violations is most places are about revenue raising so anything which reduces the opportunities - like accuracy and fairness - are unlikely to get much of a look in.

edit: for clarity, it looks like this http://www.mirror.co.uk/news/uk-news/pictured-speeding-motor...

also referenced in my reply below.

In the UK, speed cameras seem to be accompanied by road markings:


I always assumed that the radar was only for deciding to take and submit the pictures, the actual speed measurement (especially if challenged) would be done using the markings on the road.

That only requires the speed camera to have a reliable to 1/100 second clock which isn't exactly rocket science.

Static cameras have markings and 2 pictures are taken, normally 1/3 of a second apart. Activation is either radar or in-road inductive wiring. Neither are foolproof and pictures are supposed to be manually checked but often are not with results like this http://www.bbc.co.uk/news/uk-england-norfolk-21264281 where a claimed 50mph was actually 18 mph)

Someone did manage to appeal because they'd incorrectly painted the markings too close together. You have to check everything ! :D

how can a video possibly show where a laser is pointed at from > 1,000ft away? that seems unreasonable.

The video is required to zoom to show the driver of the vehicle as well for identification purposes. It prevents people claiming they were not the driver.

(e.g. it looks like this http://www.mirror.co.uk/news/uk-news/pictured-speeding-motor...)

That image may reasonably prove it was not a woman driving the vehicle, but no way can that prove it was the actual driver (or anyone's identity). It's way too blurry and pixelated. Also, a LIDAR beam shouldn't be pointed at a sloped window, so I doubt it actually proves where the beam was pointed at either.

I don't see how it could even prove it was not a woman driving. I'm barely comfortable asserting that it shows a human face.

Josh Bloch is always entertaining, watch some of his video talks or read some of his books. He has a couple really good talks on GoogleTechTalks youtube channel.

Me too. Though I would've been over the moon if he'd said he wore his "Back off man. I'm a scientist." shirt to court.

Agreed, this was such a treat to read. Love when science sets the sales brochures straight.

Speed radars are good for speed traps, but not so great to prevent speed related incidents. They share the same fatal flaw with all other single-point speed meters: You can just slow down for a minute, while you pass by the speed trap, and then speed up for the rest of your trip. Instead, a 2-point speed meter (i.e. license plate readers every few miles, measuring time between matching reads) system is superior because a) their margin of error is negligible and b) they measure sustained speed over a long distance rather than at a single hot spot, thus making roads safer. I can't believe it's not implanted at least in all interstate freeways.

Possibly because the cost/benefit just isn't there.

In the UK, the data shows that speeding (excessive speed for the conditions above the speed limit) is the primary cause in single digit percentage of accidents. I believe there's data from 1996 and 2007 for this, will dig it out when I'm not on mobile.

If you want to spend money on accident prevention, there's much better things to target than speeding.

I have yet to get into an accident, but I actively avoid walking across several streets in Seattle because of a combination of entitlement thinking (This road is mine because I'm in a car!), and pervasive speeding. I'm not the only one...I recently found out almost nobody on my side of a local road will cross the road due the same problem. The road, therefore, has become a barrier to commerce and has split a community in two.

Preventing accidents isn't the only reason to enforce traffic laws.

There aren't any traffic lights and crosswalks on this street?

There are some crosswalks, 8 blocks away from each other. No lights for at least a mile. In WA state, every intersection is automatically a legal crosswalk with pedestrian right of way (unless marked with a "No Pedestrian Crossing" sign), but the lack of enforcement combined with the high speeds makes that right of way effectively meaningless.

I walk a lot in CA. Not long ago I saw a cop not yield to a pregnant woman pushing a baby in a stroller, in a 4 lane road. She was in the crosswalk, clearly marked. There was no light or stop sign, but she was in the middle of the 4 lanes when the cop drove past her in the closest lane. I really couldn't believe what I was seeing.

When the cops don't even respect the laws, the laws are meaningless.

This doesn't surprise me. I walk a lot too, and I constantly see cops flip their lights on for the few seconds required to make an illegal left turn, run a red light, etc., and then turn them right back off.

Yet another consequence of police immunity from prosecution.

What road are you talking about in particular?

If it's something like 15 Av NW in Ballard, it's pretty obvious that you're meant to cross at a light, even if you legally have more of a right to cross at the uncontrolled intersection one block away. It's unreasonable to expect a highway-in-all-but-name to stop for one person when marked, lit crossings exist within five blocks at all points along the road.

In Ballard there are two. I'm specifically talking about Leary between Market and the 15th Ave overpass, but Market itself is quite the same way east of 15th.

Even in the case of normal 2 lane roads, drivers here still act like pedestrians do not have the right to cross anywhere but a crosswalk (and some don't even respect the crosswalk), and it only gets worse with 3 and 4 lane roads because that is where the drivers tend to drive significantly over the speed limit.

And yes, I do consider it reasonable to expect cars to stop for pedestrians in all scenarios where pedestrians have the right of way. A 5 block detour to cross the street can add another 15 minutes to your quick trip...what would happen if the situation were reversed? Can you imagine the outrage that would happen if cars had to drive 15 minutes out of their way? Slowing down for 5 seconds to let someone walk across the street is a miniscule inconvenience in comparison.

Hypothetically remove speeding from the equation, and keep the entitlement.

Would you feel safe crossing the road now?

Safe(r), yes. Speeding decreases the chances you will die in a collision, and decreases reaction distance.

I feel this way in the vast majority of Maryland.

Northern Virginia is that way too. Even with marked crosswalks with yield to pedestrian signs, crossing at an intersection without a traffic light is downright scary.

%of total accidents is amost meaningless. % of accident deaths or even %of totaled cars would be a much better indicator. A parking lot fender bender is vary different than an 80MPH head on collision.

Also, even if speeding is not the direct cause of an accident it increases the damage resulting from an accident.

PS: It has been estimated that hard limiting private vehicles to 40MPH would have saved over 2 Million lives in the US. Not that I am promoting such a low speed limit but people really don't understand the dangers of speed. Every year after 1945 at least 30,000 people died with a peak well over 50,000.

New Zealand keeps fairly good records which can be downloaded here: http://www.transport.govt.nz/assets/Uploads/Research/Documen... page 62 lists the percentage of crashes, crashes with injuries and crashes with fatalities. Speed is constantly found in around 30% of fatal crashes.

Saying speed is found as a factor in around 30% of fatal crashes doesn't really say much as to the effectiveness of these sorts of measures. I mean, right off the bat I have to ask - what is the overlap between "people in fatal crashes with speed as a factor" and "people who receive automated speeding tickets".

I think as a percentage it would be unimaginably tiny which supports the assertion that it is misplaced enforcement if safety is actually the goal.

And when you consider that more than 30% of drivers are typically speeding on many/most roads...

If only we were so lucky. 30% of drivers in NZ drive 20km/h below the speed limit on the motorway is more like it :|

It's not about saving lives. It's about revenue generation.

Speed limit laws don't exist to generate revenue. They exist to disincentivize speeding.

If speed limit laws didn't exist, can you imagine lawmakers saying, "We need more money. Hey, I know! Let's charge people money for driving over a certain speed!"

The laws aren't put into place with the "let's generate revenue" mentality, but their enforcement is definitely done with respect to that mentality. If it's all about getting people to slow down, then:

1) Why aren't law enforcement more focused on getting people to slow down than writing tickets?

2) Why do traffic cops have monthly quotas for tickets?

3) In places where monthly quotas are against the law, why do 'performance revues' of traffic cops only focus on '# of tickets' as the largest performance metric? (basically a quota by another name)

4) Why is it so easy to bargain down a speeding ticket in a large city, whereas in a small town they are only willing to haggle on the points on your license (hint: because they still want you money)?

How is a ticket quota any different than a SLOC quota or a SLOC analysis in a performance review?. Quantity of tickets issued is a productivity metric, as flawed as it is. Their existence does not imply that tickets exist for revenue.

Just like no community has ever been found to be shortening yellow light timers after setting up red light cameras, and no cops ever dubiously search cars for drugs so they can seize assets.

Just because they weren't conceived for a purpose doesn't mean that's not how they're used. Speed enforcement is very frequently performed by small town cops sitting on highways that are just barely in their jurisdiction. They're doing it for money, plain and simple.

See https://www.google.com/maps/preview?client=safari&q=hampton+... for proof of this.

>They exist to disincentivize speeding

Where I live, in Chicago, the speed limits are so low on some freeways that 91-98 percent of people are going over the speed limit, and the average speed is over 70mph. So everyone, including the police it seems, agrees that the speed limits here are not for my safety, but exist as a way for the officers to cherry pick essentially any car they want and write them a ticket.

The idea of a speed limit is sound. But there are organizations that work to game the system. A great example is the multitude of sleepy towns right next to highways. They have a police force that is exclusively utilized on the five miles (or less) of highway that officially fall within the town limits, writing tickets to people who pass through. For example, Lindale, Ohio has a population of about 170 people and collects about $800,000 a year from speeding tickets.

My mother got snagged in one of these in Virginia a while back - they have a hill where the speed limit drops from 65 to 45 at the bottom of it, with a specially planted copse of trees where the police sit with their detectors. A quarter mile down the road, they have a specially built parking lot for people to get their tickets. They even provide envelopes and stamps for people to send their checks! Nice people.

Virginia is also a state that bans the use of RADAR/LIDAR detectors.

I suspect that this business model is in trouble if GPS makers begin to track speed-limit information and pass that along to their users.

Speed limit laws started as a safety thing, then they were a car efficiency thing (during the 70's oil crisis). The problem is that the municipalities started to increasingly depend on the income from traffic enforcement.

No, lawmakers don't say "Hey, I know! Let's charge people money for driving over a certain speed!", they instead say: "lets install these red light cameras on this intersection that doesn't see a lot of accidents.", or "this long straight stretch of highway, with few accidents, but lots of speeding should be better policed". The enforcement of laws becomes more about making money from the tickets than from concerns about safety.

The manufacturers of speed cameras take a percentage, and it is a windfall for the municipality.

I live in an area where stationary speed cameras are around every corner (Montgomery Co, Maryland). I've lived here long enough to know that there's no way the county would spend money on the equipment and man power to maintain and operate that network, just to break even for the sake of safety.

Don't be ridiculous, If it was about revenue there would just be more toll booths.

That would only be the case where people accept tolls & toll booths on roads as an acceptable thing.

Sure, they're common in Canada and the US but in some other countries they lead to years of civil disobedience, protests and eventual scrapping by newly elected governments : http://en.wikipedia.org/wiki/Skye_Bridge#Toll_controversy

Speed fines have the semi-respectibility claim of trying to reduce accidents/dangers on the road (with some validity).

I'm waiting for someone to calculate the greenhouse gas emissions created by toll booths.

Tolls booths are obviously about the revenue, which make the voter angry.

Not that I support his claim, just refuting yours.

Even if it's not the primary cause, accidents are much more dangerous at higher speeds. It also makes reaction times shorter for avoiding other things.

"I can't believe [average speed camera systems are] not implanted at least in all interstate freeways."

Possibly because a civil society, favoring the preservation of a measure of basic autonomy, does not implement every measure for tracking, enforcing, circumscribing, and monitoring the people.

In practice, they're actually very good for improving traffic flow on busy roads - because almost everyone is driving at the same speed, jams just don't form in the same way. The utilitarian argument for them is very strong.

  The utilitarian argument for them is very strong.
Doubtless a national numberplate recognition system would be effective at enforcing the speed limit.

Once we have it, it would also be of great utility to investigate kidnappings and terrorism. And serious and violent crime. And vehicle thefts. And drug trafficking. And driving without a license, insurance, or tax. And lying about your address to get your kid into a good school.

And who could object, when we're already storing proof of what really happened, to that proof being used to vindicate the innocent in a divorce hearing, or an employment tribunal?

As faithful believers in the free market, what better way to fight congestion and encourage the use of public transport than a tax that only applies on congested roads, and only at peak hours of the day? What luck, the infrastructure is already in place.

No doubt the system will be expensive to design and operate. It would help defray the costs if we release citizens' travel records to some carefully vetted partners, such as academic researchers, urban planning consultants, insurance companies, marketing companies and credit rating agencies.

We already have numberplate recognition and its essentially on a national scale, just not completely linked up from jurisdiction to jurisdiction. License plate scanners are becoming rampant in some areas, they apparently have never been successfully blocked, all for reasons you listed and also as "license plates and vehicles don't have rights". The favored method for abusing a person's rights is to target their things

Perhaps I can incorporate my car, and get it some rights!

Do you have evidence to back up that claim? It seems counterintuitive that slowing down the top few percent fastest drivers would improve traffic. If there's enough traffic to cause congestion wouldn't they be stuck behind slower drivers anyway?

As you go faster, your stopping distance (that is, the distance you should maintain between you and cars in front and behind you) increases. This leads to roads having a maximum capacity somewhere in the area that speed limits are set. If you go faster than that, you're reducing efficiency of traffic.

Anecdotal evidence, but it also makes intuitive sense if you consider that vehicles travelling at a range of speeds and particularly changing lanes to overtake the slower drivers is effectively a turbulent flow. If that flow can be smoothed, as a body it travels faster.

I know the trucking industry regularly criticizes the safety implications of having a separate speed limit for them, as it makes lane changes much more complicated. They aren't impartial to the financial impact of the speed limit though, so there's that.

In France they have a system that sort of works like this, most/many highways are toll based. There are toll booths at regular intervals(every 100 miles or so). If your time between toll booths is below a certain time, they know you were speeding at some point. To get around this, my always speeding grandpere would just have us stop for gas, un cafe, etc right before each toll booth.

> To get around this, my always speeding grandpere would just have us stop for gas, un cafe, etc right before each toll booth.

That sort of defeats the point of speeding. Why endanger your lives and the lives of the others if you even don't get faster to your destination as you make additional stops to "defeat" anti-speeding systems?

I don't think his speeding was a logical, reasoned thing

You are supposing he stops for gas when his tank is full?

I'm supposing he stops for gas when his tank is still more than half-full to top it up, so that he stops exactly enough times to avoid being fined for speeding.

The one I've seen were not installed on the toll booths themselves (those are only there when entering or exiting the freeway) but on separate kind of portals above the road.

A camera records the traffic, a computer extract the plates. Then later you have the same setup, and they can then calculate your average speed between the two. The French name is "radar tronçon".

> I can't believe it's not implanted at least in all interstate freeways.

If you're around DC, there are a bunch of automated speed detectors built into the highways, and it's the same story: People slow down for the trap, and then speed up afterwards.

If you're from out of town, you're pretty well screwed because you'll be following some guy who will, out of the blue, slow down for no apparent reason.

Interestingly the system you describe, marking two points and measuring time between them is illegal in California:

Definition of a speed trap: http://www.dmv.ca.gov/pubs/vctop/d17/vc40802.htm

Speed traps are prohibited: https://www.dmv.ca.gov/pubs/vctop/d17/vc40801.htm

> I can't believe [average speed detector is] not implanted at least in all interstate freeways.

They are very common in Australia. It takes a photo of your license plate, then another 10km (or whatever) down the freeway. If the two photos are less than x seconds apart, you get a speeding ticket.

I was going to say something similar. However, the ones I have seen are only applied to large trucks. So far, at least, cars can speed through with impunity.

The Melbourne->Geelong road (Australia's busiest, and deadliest) has many, and they will ding regular cars.

They also have these in Norway. The 2nd camera has a light on it and will blink yellow if you should expect a ticket in the mail.

I expect to see a post about time synchronization problems with remote equipment.

The Mean Value Theorem strikes again!

Unfortunately, because police departments are often (mostly?) funded by things like tickets[1], they actually have an incentive to care less about traffic safety in this case. If the goal was truly to get people to stop speeding the municipalities could increase fines to a level that actually serves as a deterrent.

1: I only have second-hand/anecdotal knowledge that these departments are funded by fines. Still, I believe my point remains.

I think the punishment should reflect the crime.

If fines and or punishments are used primarily as a deterrent, then why not just have huge punishments all over the place?

Do you see how that's immoral? Fines should be used as punishment, not deterrence (punishment is a form of deterrence, but is merely a side effect). If I decide to litter, it's because I think "this is not that big of a crime. I'm not harming people very much." It's not anyones natural moral instinct to think, "I would do this, but the penalty is to high" - we're conditioned to think that. But as is all to often, a lot of times people are not even aware that their actions may be illegal, or may not be aware the consequences are vastly harsher than the crime. Do you know what the penalty is for driving with one bad headlight? me neither. I hope its reasonable, especially when I make the decision to do it, but I base the decision off the fact that driving without a headlight does not seem that egregious of a crime.

So shouldn't our punishment system be base off the same thing that people use to guide their decisions? The results of our actions?

The answer is yes. I don't want to live in the world you are imagining. Even if there is no litter on the ground and no one speeds.

If you say, just inform everyone of the laws really really well so they know beforehand when making a decision, that is utterly impossible. Foreigners exist. People are busy. All laws are not even totally known to the lawmakers. It is an impossible task.

Back to your point: If the goal was to stop speeding, they would make it physically impossible to speed. Either by really pervasive robotic enforcement, or governors in cars. But they don't do that, they want the money.

Still, the punishment should reflect the crime, even in the robotic police world.

Perhaps it's because you're ticketing the vehicle's registered owner, but not necessarily the driver.

That argument works in some countries while in others it doesn't. In UK only people who are explicitly listed on the insurance document can drive the car, and the police can demand that you tell them who was driving the car at the time. In some other EU countries like Poland, you buy insurance for the car,not the driver,so literally anyone can drive it(with your permission of course). Then if you are caught by a speed camera and your face isn't visible you can say that someone else was driving and you don't remember who - in theory there is a penalty for not saying who(200zł = ~$60), but most people opt to pay it instead of the speeding ticket which can be higher - or go to court and dispute that they cannot pay for the crime they didn't commit and they cannot be forced to remember something which they don't remember - and they sometimes win.

> In UK only people who are explicitly listed on the insurance document can drive the car

That's not entirely true, it depends on your insurance. It's an offence to drive a car without insurance, and an offence to allow someone who is uninsured to drive your car. Some insurance policies do not extend the insurance you took out to driving other peoples cars. However, some fully comprehensive policies do have third party insurance while you are driving someone else's car with their permission. In that case it's fully legal to drive.

Ok, I didn't know that. Still, it works another way around than it does in countries like Poland - you have to have your own insurance,to drive somebody else's car. While in Poland you only buy insurance for the car,and anyone with a valid drivers licence is automatically covered by the insurance purchased for that car(unless they are doing it without the permission of the owner, in which case the insurance is invalid).

I don't get why people are bringing this point up like this was something weird, IMO it should be obvious. You own a dangerous kinetic weapon, you should be responsible for how it's used, either by yourself or by anyone who you lend it to.

As someone who daily drives a highway [1] that is marked 15 MPH below what it ought to be (as almost all highways are), I hope this system never comes to fruition.

Now, automated tagging of morons who stare at their phone while driving? Bring it on. Those fuckers are a plague.

[1] The Mass Pike (I-90); which is a toll highway that is marked 65 MPH, on which traffic averages 75 MPH, and 80 MPH is well under the speed the highway can safely support (given attentive drivers).

On the other hand, as someone who also believes speed limits are too low, I sometimes wish they _were_ enforced to draconian extremes because then the 95% of drivers who just ignore the law instead of trying to change it might actually get off their asses and vote.

Likewise, I secretly hope vehicle speeds would be electronically limited (say, radio-controlled by highway transmitters) for the same reason.

> (given attentive drivers).

Good god man, since when is that a given? The situation worsens with each passing day.

Hence my assertion that police should crack down on such inattentive drivers.

2-point speed meters would work especially well on toll highways. They already know exactly what time my car go on and off of the MassPike, but if you cover the 60 miles in 30 minutes then you get charged the same $5 as always.

This can be intentional. If there is a dangerous piece of road where the average speed of traffic is higher than the road will take, then put a trap in to slow the traffic down to the limit. It doesn't have to be over the entire highway system to have an effect on accidents.

For example, in NZ, there is a speed camera half-way down Ngauranga gorge in Wellington - a place where there is a blind turn down a steep slope and where the limit goes from 100kph down to 80kph.


It's not the speed that is the problem - it's the relative difference in speed between two nearby vehicles that you should be concerned. Someone doing 55 in a 55 when everyone else is doing 70 is being a hazard, in their case following the speed limit is outright dangerous.

This is of course in context of freeways - residential streets etc do require a hard speed limit.

If you've traveled around the country, you've invariably come across those "speed is monitored by aircraft" signs, and what you described is how they do it (tracking how long it takes cars to go from point A to B)

In California the CHP (California Hwy Patrol) plane has to do the same thing the CHP car would have to do: match your speed and then note its own speed. Measuring time between points is forbidden no matter what the observer's vehicle is. Radar is also used from the ground but was not available to CHP when they started using aircraft. The planes are on the inexpensive side so sometimes they have to dive to achieve the speed. Also recently CHP got to use radar statewide so they don't use aircraft so much.

I've always been a bit nervous about those "speed is enforced by aircraft" signs (as opposed to "monitored"). I always get a mental picture of a aircraft strafing near my car until I slow down...

You may enjoy this image from XKCD then:


Yeah, but the initial ones in the UK were lane based (SPECS?), meaning if you changed lane at any point during that section, they wouldn't work. I assume this has been fixed now?

If I recall correctly, for reasons I don't understand, this is not only not implemented in California, but not even legal there.

The fundamental reason is because drivers feel entitled to speed and most voters are drivers. People with expensive cars further believe they've paid for the privilege of violating more laws more often, and those people are also more influential in policy setting.

There are lots of expressions of this fundamental reason, such as people throwing a fit about automated license plate reading in the name of privacy. But our all boils down to the fact that a person turns into a sociopathic scofflaw as soon as he gets behind the wheel.

OR it could be because speeding isn't that dangerous and the current limits on most roads don't represent what speed people actually drive at or what speed people could safely drive at.

It's different on residential streets, but on freeways I think the way Germany handles it is better. Speeding tickets (and most traffic violations really) are not about safety or curbing behavior they're about generating revenue for the town/city.

A Dutch engineer once told me (back before 2004 I guess ) that they once raised the speed limit on the roads in Netherlands only to find average speed decreased.

His explanation IIRC was that 1. once people broke the limit it didnt matter how much and 2. when speed limits felt more correct more people respected them.

I'd love to know if anyone has any pointers to research on this as around here speed limits are weird. (80 in places where you obviously can't even drive 80 and 80 on the highway, -four lanes)

I used to live in Los Angeles. On the freeways, the speed limit was 55mph but I read once that the actual average speed was around 17mph.

My (unscientific) theory is that with higher speed limits, you get more traffic waves, and people try to change lanes more often, causing delays.

If the speed limit on LA freeways was only 25mph, I would hope that people would chill out and the traffic would flow more smoothly, resulting in a faster average speed than at present.

Look up "rolling speed harmonization," an attempt to mitigate atrocious traffic to and from the mountains here in Colorado by using a pace car (effectively a strictly-enforced lowered speed limit).

Initial "tests" with lighter traffic conditions proved that the system helped stabilize closing speeds and volume, but in the actually troublesome heavier traffic conditions the state has been unable to figure out when and where to deploy the pace vehicles effectively.

Be careful with your average speeds. I often drive in excess of 70mph on the (65mph limit) freeway in LA, and I am far from the fastest car. The key difference is that I don't drive in rush hour. A 25mph speed limit would be absurd.

Speeding is extremely dangerous. It's ludicrous to argue otherwise. A third of crashes (including fatal crashes) involve speeding, and the faster you are driving the more likely you are to die or fatally injure another.

Also, changing the speed limits on roads have been studied and it doesn't make a humongous difference. The government usually sets the speed limit at slightly lower than the average speed people actually drive.

> Speeding is extremely dangerous. It's ludicrous to argue otherwise.

Actually, blanket arguments like "speeding is extremely dangerous" are ludicrous. "Speeding" is exceeding a semi-arbitrary speed threshold. If that threshold is, say, 70 mph I'm OK at 70 but if I go to 71 I am being "extremely dangerous"? 71 is speeding in that case, after all.

> A third of crashes (including fatal crashes) involve speeding,

If a third or more of all drivers speed, that statistic is meaningless.

> the faster you are driving the more likely you are to die or fatally injure another.

Indeed, and that statement has nothing to do with speeding. It is a continuum from 0 to whatever the top speed of a given vehicle is. This statement is equally valid when you are under the speed limit.

> Also, changing the speed limits on roads have been studied and it doesn't make a humongous difference. The government usually sets the speed limit at slightly lower than the average speed people actually drive.

I have seen that happen before, but in my experience that is the exception rather than the rule.

A third of people driving are speeding.

"The government usually sets the speed limit at slightly lower than the average speed people actually drive."

I don't think you've ever driven on a US interstate.

> the current limits on most roads don't represent what speed ... people could safely drive at.

If there's a sidewalk or any t-junctions, that's about 20mph tops. Anything faster, and you can't stop in time, plus in a collision, kinetic energy goes as the square of the speed.

For local trips, with stoplights that slow you down anyway, driving slower adds only a few extra minutes to your journey time. Personally, I'm not seeing the need to be so hurried all the time.

http://www.rospa.com/roadsafety/adviceandinformation/driving... http://blog.americansafetycouncil.com/why-speeding-is-danger...

I think the GP is talking about speed limits on controlled-access highways, not on residential or commercial streets.

I'm not sure speed traps are preferred by voters over a 2 point system. I can say that as a driver I'd much prefer the 2 point system instead of the vast quantity of speed trap radars we have in france right now.

I think the main difference is the price, especially since 2 point systems turn into n-point systems if you have a lot of intersections.

  a person turns into a sociopathic scofflaw as soon as he 
  gets behind the wheel
Boo this man!

That is an ideological position, and I could easily apply the same blanket label of absolute sociopathy to law enforcement, and I'd be just as wrong.

But there's a difference between a mechanized, automatic law enforcement system and a law enforcment system that is implemented as a practice performed by living human beings. The human version is prone to imperfections and corruption, yes. But mechanized, automated law enforcement really COULD express a perfect ideology and attempt to enforce it perfectly, with an unforgiving brutality, which could not otherwise be accomplished with the complicity of human beings. Please understand that difference.

If you think placing a human being behind the machinery of an automobile is automatically bad, think about what it might mean to place a human being behind the machinery of a fully automated law enforcement system, with that same lens of blanket sociopathy.

Sociopathic? Maybe not, but scofflaw? Most definitely. Drivers have a really hard time with really basic things. Speed limits, red lights, turn signals, proper lane etiquette, and other common courtesies.

Every single one of those things has a law attached. People either forget or think that the law doesn't apply to them.

I'm a scofflaw every time when I approach the computer and/or (not) read terms and conditions or license.

As are most of us.. however there is no point at which ignoring the average EULA will endanger a life.

People who speed, hang out in the left lane, run red lights, don't signal their turns and lane changes, and so on are a danger to themselves and others.

LIDAR sucks and there is no judicial notice on it in California. If you ever get a LIDAR ticket, do a trial by written declaration (or TBD). Just state that you dispute the validity and accuracy of the LIDAR reading and they'll usually throw it out. Remember to ask the officer(after he has given you your ticket) what model laser/radar detector he was using, and at what distance he measured you at. Anything over 800/1000 ft(this is really close, and rarely do they get you this close) will usually automatically be struck down if you question LIDAR's validity at that distance. That is a case you will win every time, if you do it right. The court cannot prove it's accuracy at these ranges and they know it. Also, rule of thumb, all CHP officers have laser only on their bikes now. source: I used to have a Lancer Evolution

>> Remember to ask the officer(after he has given you your ticket) what model laser/radar detector he was using, and at what distance he measured you at.

That's an interesting point. Would that be admissible, though? Wouldn't you saying "He said it was at X feet" would be considered hearsay in court, versus a cop saying "I took a reading at X/2 feet"?

He/she should normally write it on the ticket(pretty sure they have to, it's always been there on tickets I've seen), but if you can get him/her to say it out loud, it's evidence that you can probably use against him/her. Also you should record your interactions with all officers. My final not a lawyer advice on beating speeding tickets: shut your mouth and don't answer the officers questions. If the officer asks how fast you were going, nothing you can say helps you, especially "I don't know". Just do your best to be polite, but firm, and don't give him anything more than a nice attitude

This isn't always the best strategy. If you're unlikely to make a court date, being remorseful and apologetic has a decent chance of getting you a reduction from the officer. If you play hardball, so will he, then you have no choice on going to court if you want a reduction.

If you're in serious trouble, STFU is the correct choice, but it's not necessarily the most economical for a moving violation.

In Virginia, all moving violations are arrestable offenses, so I grew up doing STFU. My understanding is that most states are not that way though.

Lawyers can also challenge the officers experience/training with the device as well as the last time the device was calibrated to be accurate.

As a college intern at a national lab my boss' boss got a speeding ticket on the military base we worked on. He spent some time doing research and when he presented his evidence in court the judge apparently told him he wasn't going to have to pay the fine but the judge wasn't going to find him not guilty because he wasn't going to risk invalidating all speed gun findings. I don't recall if it was lidar but it's funny the stories are so similar. It's hard to use technology to mess with engineers. :)

Lower courts (even in the Military) can't really establish any meaningful precedence

If you were really gung-ho about getting it marked as not guilty, could you appeal it and move up the chain?

I think he missed a couple important points. The sweep effect, shaking and aiming are more amenable to signal processing than it seems, depending on the resolution and noise in the system. I tried to illustrate in pictures:

1) Just to demonstrate that a nonuniform sweep is amenable to detection or processing, consider this picture, with the correct estimate in green: http://imgur.com/FsPAwCn

2) Now imagine the device is more sophisticated. Consider it has a very large resolution around the incoming pulse: http://imgur.com/z8UrhUw In this case the beam width is actually beneficial, and so are large distances. The sweep effect would cause a shift in the peak intensity shown in the graph, but the object depth frustrum should be clear across samples (and dislocating at t'=t-v*dt/c).

3) Officers can be trained to recognize situations unforable, regardless of distance. One fast car passing a slow one would make it easy to confuse the equipment. A clear desert however doesn't present many threats for error.

I think its funny how he claims location sampling at different times is not a measurement of speed.

It's strange how he mentions the sampling speed, but then pretends it's 1/3 second. Basically what he is attacking is the worst design of a speed gun that he could imagine from the public information. A more fair challenge would be to find sufficient error from a competent design of a speed gun, but then it wouldn't be as self serving.

When I was a teenager I tried to fight a speeding ticket, and prepared a presentation like this with several good points (I think).

Come court day, I got all dressed up, stood up when called and started my arguments ... and the judge simply cut me off after two sentences and said "guilty".

I'm surprised this guy was allowed to present his whole argument and it actually convinced a judge.

From the beginning, it sounds like he's presenting this to a group of people invited by his lawyer, and the lawyer took care of the actual ticket resolution.

Did you appeal? You can always appeal your first court hearing. The key is to talk to the prosecutor beforehand. They will almost always plea it down.

This was in Maryland. It seemed you went right to the courtroom and talked to a judge along with 40 other people. There was no prosecutor present as far as I could tell.

I've fought them in Connecticut later and there you only meet with a prosecutor and they warn you all over the place that if you don't take the deal and try to go to court the judge can significantly increase the fine :-(

This presentation was not to a court; see slide 51 for the resolution: his attorney bargained it down to a zero-points violation before trial.

I'm sure it was valuable lesson for you that law is not concerned with the truth as much as it is with order.

Can anyone tell me why speeding tickets aren't enforced with video cameras (like red-light tickets are)? It would seem to be much more accurate, much easier to enforce, and much harder to dispute.

Irrespective of the rights or wrongs of speed limit laws, I do believe that consistent and efficient enforcement can only be a good thing.

The goal of speeding tickets is revenue generation not lowering speeds. It's essentially random taxation on people who drive quickly.

Because of that they need mobile, disguisable, hand held units. Video from a handheld unit wouldn't be great for determining speed.

Now, they could easily create combination LIDAR-Video boxes and mount them above traffic for clear speed calculations. But then people would learn where they are and drive slowly at that location so it wouldn't generate any revenue.

In fact it might actually cause accidents because drivers might slam on the breaks when they get close.

In Kansas City, Missouri, they installed a bunch of red light cameras and a bunch of false cameras (just boxes mounted on stoplights to look like cameras). The real ones and fake ones were published quickly (with whether they were real) and it had 2 major consequences. First, the traffic courts were quickly overwhelmed with challenges, and it became normal to wait 5-7 months before getting a court date for running a light. Second, several of the intersections with cameras saw a quick increase in accidents, as people were so terrified of a ticket that they would not worry about being rear-ended when stopping very abruptly.

> The goal of speeding tickets is revenue generation not lowering speeds.

This depends on the country. In the US and Canada it certainly can be and is a cash grab, but in Switzerland, for example, it's not. Fines are in place, but they are also almost always accompanied by deterrent measures as well. Going 120 km/h through a tunnel where the limit is 80 km/h can earn you a week in prison sleepovers (that is you have to go to the prison for the night) with all earnings for that week withheld as a fine. Also, there's a lot of stationary speedguns, which you can spot at a distance. I also saw semi-portable automated speedgun that was placed in a specific spot where people tended to go over posted 60 km/h limit. It stayed in place for a week and then was removed, presumably after the average speed dropped to the limit.

In Ireland we have a system where you can contest any of these automated fines in court. The problem is that the fines and penalty points double should you contest and lose. http://en.wikipedia.org/wiki/Penalty_points_in_Ireland

How is that even legal? It seems like it would infringe on the requirement of due process anywhere in the world.

That's just a more formalized version of a plea bargain. (Whether plea bargains are just as much a due process violation is not part of my post.)

In an effort to force people that can't afford to pay a double fine from seeking justice through the legal system? Nice.

It's funny that they make it like a game. Actually it's a lot like challenging a word in scrabble.

Alternately, you could change your name to Prawo Jazdy.

Speeding would require the police to record/archive video, vs. just a single photo which contains both your car being behind the white line and the red light.

Also, the red light ticketing programs are often administered by private companies, without officers being involved. Speeding ticket video would need to recorded by the police.

All that said, I think its a great idea and the obstacles can surely be worked out.

Finally, a tip: if you are ever pulled over and you plan to dispute the arrest, request the officer's dashboard video ASAP. This will ensure it is preserved and available for you at trial; if you don't request it quickly enough it might not be available when you do. Don't count on it being around even a week - request it the very next day.

Because video cameras are arguably illegal. You can't face your accuser in court, therefore it should be thrown out.

Got a speeding ticket from one of these lovely cameras in the state of Iowa, then I was sent a bill from some company in Phoenix with bold threats that if I didn't pay the fine, it'd be submitted to a collection agency and negatively impact my credit score (because otherwise I'd just have not paid it. I'd happily live the rest of my life without ever entering Iowa where they could arrest me with a bench warrant)

It's corrupt, illegal and immoral. However, since I (like most people, I'd wager) don't have the time nor energy to fight, I paid my $200 fine and moved on.

This is a common myth.

The camera is not your accuser; the state is, using the camera as evidence of your violation.

It would be no different than a security camera catching you breaking into a building. The camera doesn't sue, the owner of the building does.

Moreover, I'd think it would be quite trivial to place the camera in the court room if any judge were to seriously consider that defense, while the camera furiously exerts its right to silence.

Testimony from a witness that no longer presents information when questioned isn't a very good witness.

The "right to face your accuser" refers to witnesses. The state is _always_ the prosecutor in criminal cases (in the US, IANAL).

So what happens when you are caught breaking into a building, and the camera is evidence of your crime?

This entire line of reasoning would completely destroy any kind of automated crime detection (security systems, security cameras), which is ridiculous on its face.

Further, what happens when you commit a crime where there are no witnesses? People are rightfully convicted of crimes based on "things" rather than the testimony of a person who saw it, regularly.

In order to introduce the video as evidence, they have to put somebody on the stand who will explain how the camera works and so on. And right there is your opportunity to confront them. You can ask all sorts of questions, like when was the last time they cleaned the lenses.

I'm going to need a source on that. I'm pretty sure a video can be entered as evidence without any actual witness to present it. Maybe you live in a state with unusual rules.

Google "entering evidence at trial" and then click on just about any of the first ten results. They all lay out roughly the same procedure.

> Further, what happens when you commit a crime where there are no witnesses?

Someone testifies as to what they've witnessed that makes them believe you are guilty, giving you a chance to question them about any flaws.

Okay. And how does a speed/red light camera preclude this?

IANAL but I don't believe it does. In a criminal trial introducing one as evidence would require some substantial effort (witnesses testifying to location, lack of tampering, etc), but I believe (again, IANAL) that generally states treat camera violations as civil, thus avoiding this work. Whether that's a good thing or not is a different question.

This is not a myth. The government wants people to think this because they don't want the veracity of the camera being questioned. That would be too fair for a system based on cash-register justice.

Its just extortion, not even law enforcement.

"We saw you do this, pay us $50 and it goes away. No insurance report, no evidence, nobody knows."

Law enforcement does this all the time, so does the mob. Its not even worth it to fight it (economic speaking), the time you'll spend out of work, stressed, etc. Then if you get a lawyer involved. You'll end up spending >$300 in time and money to not spend $50.

> Because video cameras are arguably illegal. You can't face your accuser in court, therefore it should be thrown out.

You can go to court and ask to challenge the evidence the camera has provided.

I think that's how it works in the UK. When the lidar detector catches you speeding it fires off a camera that takes 2 photos of the vehicle a set time apart. The car's progress is manually compared against a gauge painted on the road surface to see if you travelled far enough in the time between the 2 photos to have been speeding. This catches those times when a lidar detector gives a false positive.

One word: Discretion

"Confronting Automated Law Enforcement" http://robots.law.miami.edu/wp-content/uploads/2012/01/Shay-...

That's a pretty short summary of a 44 page document. Can you elaborate a little more?

Sure. Do you want to live in a world where every time you violate the letter of the law you're penalized? Before you answer, consider that you're going to have to keep 100-200 years of law hot in memory to ensure your daily compliance.

Why bother asking a question when you word it in such a biased way? Obviously my answer is yes, that is the world I want to live in.

Because that's a terrifying world to live in.

I am biased. To accept the idea of compliance with the law to the letter constantly is unreasonable. Roll 1-3 feet over the white stop line? Ticket. 1-2mph over the speed limit? Ticket.

I hope this information, or the equivalent, filters into the awareness of judges. I was in traffic court in Virginia last year and, as I was waiting for my case, heard the judge explain to several defendants who were there to challenge their lidar tickets that the lidar was essentially infallible and could not be confused by other cars on the road. And this was an intelligent judge who seemed unusually sympathetic to the accused.

Unfortunately judges are people and if you have tons of people coming in with just "LIDAR is not accurate enough to prove reasonable doubt" compared to cops bringing in studies proving their accuracy it is difficult to listen to it.

Anecdotally, I heard of an astronomer in a similar situation, who attempted to prove the radar gun used to "catch" him speeding was incapable of measuring the speed accurately enough (presenting info on the radar gun's sampling properties and on sampling theory; I forget the specifics). Supposedly the judge maintained the speeding violation but reduced the man's fine for "entertaining the court".

Josh Bloch is awesome.

For the non-java inclined, he wrote (among other things) java.util.HashMap. Most all Java programs run (lots) of his code.

I know him as the author of the awesome "Effective Java"

I know him as the guy who advocated the even wider use of factories...

In Michigan, a speeding ticket is a civil infraction, not a criminal offense, so the legal standard is preponderance of the evidence, not beyond a reasonable doubt, as the slide deck says. I suspect it's the same in California.

In CA, infractions are crimes so the reasonable doubt standard applies. See Cal. Pen. Code section 16. http://law.onecle.com/california/penal/16.html

Wait a minute, if that's true won't it imply that traffic violations/infractions convictions get you a criminal record ?

Yes. Infractions are crimes so yes. For the most part, they are not treated as crimes. You cannot be jailed based on an infraction. Most job applications I've seen typically explicitly exclude requiring information about past infraction violations.

I have lidar jammers on my car, but Arizona doesn't use a lot of lidar. (Motors and sometimes bored DPS will, but typically it's Ka band radar via Stalker Duals.) Not really knowing how lidar worked, except that a "laser" pulse hits the car and reads back a speed, this article was great because it explains that the measurement process is far slower than you'd think (0.3 seconds!) which is easily enough time for my jammer to detect the inbound infrared and start spamming light on that frequency, which is what they do.

I don't think I've ever successfully jammed one, since again, AZ is mostly Ka, but it's pretty neat to know that they can work as advertised (since they're built in to the front of the car most likely to be targeted by lidar).

I've read that in some jurisdictions police have started confiscating jammers and even charging users with obstruction of justice, on the theory that while owning them is explicitly legal, using them prevents police from carrying out their duties. Do you know what the history in AZ is like?

All the talk in this thread about various forms of speed management and fines remind me of an article I read a while back about a Swedish test program that used fines from speeders as the funds for a lottery that people driving at or under the limit were entered into automatically: http://www.wired.com/2010/12/swedish-speed-camera-pays-drive...

The highlights:

1. Lidar gun manufacturers test them on limited and ideal circumstances

2. Beam divergence and shakiness make them less useful past 1000 feet, which is generally acknowledged.

Excellent presentation with considerable technical information, e.g., weaknesses in the LIDAR approach, operational realities that reduce accuracy, etc., and some legal background, e.g., limiting LIDAR to 1000' or less in some jurisdictions - but contrast with overall lack of case law.

Could be of value to anyone wishing to fight a ticket.

Perhaps anyone can explain me why Lidar is not dangerous to sight?

Whenever you see anyone working with lasers they'd wear protective glasses. Now I realise Lidar uses infrared wavelength which is not visible to us, but that does not mean it's not dangerous, or does it?

Non-visible lasers pose a much bigger hazard than visible. Intense visible light triggers an involuntary defence called the blink reflex whereby we blink before the retina absorbs enough energy to get damaged. Lasers outside the visible range don't trigger the blink reflex and can destroy the retina before you know what happened.

Lidar operates at relatively low power and relies on very sensitive detection in a very narrow wavelength range to identify reflections.

The reading was taken at a distance of 1300 feet with a handheld device that is not meant to be used handheld beyond 1000 feet. That's a significant distance. I'm assuming the cop was hiding or trying to stay hidden.

A lot of this is common knowledge now. You can check out guys of LIDAR who research these types of guns & how accurate their findings are. This is also why cops should be taught to do several speed readings & to point at the vehicle, not the headlights. Also, depending on the paint, it can also cloak the vehicle's speed or make it take longer to get back to the gun.

Next time I get a parking ticket, I'll be sure to investigate the temperature stability of the parking meter's clock.

I'm surprised the angle of measurement never came up. Isn't it the case that a reading has to be head-on for it to be accurate? It seems pretty obvious that at higher angles the observed distance delta will be smaller.

I've wondered sometimes if it would be possible to fight erroneous speeding tickets using the repeated GPS pings your phone or nav unit makes while using them for directions.

Well, he fought with half science: he came up with a set of testable hypotheses, but didn't actually run any of the tests. I guess that's as scientific as cosmology :-)

I think all he way trying to say that there are ways that a LIDAR gun could give a false reading, and there's no current incentive for law enforcement/manufacturers to ensure accuracy. In fact there's an incentive for both the manufacturer to emphasise accuracy based on successful prosecutions, and for police to emphasise accuracy to prevent large-scale contesting of tickets.

They are used for law-enforcement, but presumably aren't available for public scrutiny, especially around 'proprietary' algorithms. As mentioned, they can get firmware updates that change behaviour, yet that doesn't make it out into "does this mean it was mis-behaving before, therefore I should dismiss tickets issued in situation X".

It's similar in some ways to vote counting machines. If they are used in public elections, then the inner workings should be available for introspection to ensure correctness.

Where are you people getting your information that they aren't available for public scrutiny? Has no one ever heard of Guys of LIDAR? http://www.guysoflidar.com/

Granted, they can't dump the firmware these devices use but they are very telling in what these detectors can pick up, can't, real world examples, and so on.

I hadn't realised they were commercially available as well. No I hadn't heard of guys of LIDAR, good to know there's someone out there fighting for the little guy.

What stops them from dumping the firmware? Technical or legal limitations?

I've wondered this too & I've reached out to them several times to no avail so either it's dead, they stopped doing it, or something happened. I'm trying to see if I can get a hold of a cop friend or two to see what the options are to legally acquire said LIDAR guns for tests. It would be a really cool project, even in the short hand.

He doesn't have to prove his innocence, he just has to convince a judge that there is reason to doubt that the LIDAR accurately reported his speed.

It's not even half science, it's just a big slide deck of FUD padded with a healthy amount of entitlement.

Be honest with yourself: If you got a ticket where the indicated speed was massively different than the speed you were actually travelling, you'd fight it too. And you might do some research into the validity of the reading, as well.

You'd especially do it in a state where the law says "x" mph over the limit and your license may get suspended (meaning you walk for 60 days). It'd be worth fighting for.

Especially if it were in a residential area where you had been deliberately careful. If I got a ticket saying that I'd been driving 40 in a 25 zone, when I had been carefully watching my spedometer at ~20s, I'd feel pretty wronged.

I'm not sure I'd have the resources to fight it, but I would certainly want to.

Can you cite some parts which reflect entitlement?

FUD, eh? So that's Fear, Uncertainty, and Doubt. I don't really see any fear, and I hope that any legal defense is going to push pretty heavily on uncertainty and doubt. Don't quite see the problem.

So regardless of the science behind it, what is the successful legal forum / mechanism to raise doubt about the accuracy of the technology being used by police?

How does the officer confirm which vehicle the LIDAR selected? I have never been clear on this point.

Having fought a LIDAR ticket before, the officer simply claims that he or she targeted your car and the judge admits the claim as a fact without question. Any attempts on your part to question this will be met with a reminder that the officer is Certified and Trained and you are just a random person with no qualifications to question the officer's abilities.

You can ask the officer if there was a wind that day, and if so how heavy. You can ask if the officer used a tripod or held the gun freehanded. Even if the officer admits that there was a heavy wind, the gun was used freehanded, and he or she pinged you in traffic at 950 ft, the judge will still accept the officer's word that your car, and only your car, was targeted.

Why? Because it's easier for the court, because they know you can't prove without a doubt that the officer targeted a different car, and because it is an important source of income for the city or county which has summoned you.

It's a scam, but it's one which Americans in general are comfortable with because it gives them the illusion of safety.

I believe they have "sights" and are aimed like a gun.

Cops routinely shoot innocent bystanders.

now if only somebody published a similarly powerful defense on "traffic control device violation" :)

Well the author may be a clever computer scientist but he knows nothing about physics and LIDAR equipment. Pathetic I'm afraid.

Given that (1) you're an expert in these areas and (2) you found no points in the author's work worth refuting, I guess it follows that the author is actually an expert as well.

Why do HN mods keep changing the title from meaningful ones, which make the reader interested in the content, to generic, vague ones? You'll see that there's definitely a correlation between the moment that HN mods change the title and the post dropping off the top frontpage spot.

I'd really like to see more transparency when it comes to title changes. The most recent case where one of my submissions had a title change mirrors what kudu is describing here: a meaningful (and I think accurate) title changed to a generic and vague one -- followed by a rapid decline in the rate of upvotes. I think there are legitimate reasons for title changes, and I think that the Hacker News mods generally do good work. But sometimes they seem to be fixing stuff that isn't broken. I realize titles in particular can be really subjective, but that's one reason I'd like to see a comment with the old and new titles whenever a title change happens. That will allow the community to chime in when maybe the title change wasn't an improvement after all.

"I'd really like to see more transparency when it comes to title changes."

I think dang is working hard to be transparent about this topic. You can see a number of examples of this by reading through the following search result [1].

Cases in point:

He has reverted titles to their original form... "Ok, we'll change the title back again." [2]

He is open to suggestions...

"If anyone suggests a better title, I'll change it again." [3]

"That's a fair suggestion and we changed the title accordingly." [4]

"We'd happily change the title if someone can propose a more accurate and neutral one." [5]

[1] https://hn.algolia.com/#!/comment/forever/0/author%3Adang%20...

[2] https://news.ycombinator.com/item?id=8050702

[3] https://news.ycombinator.com/item?id=7557464

[4] https://news.ycombinator.com/item?id=8104621

[5] https://news.ycombinator.com/item?id=7959549

Title changes are a perennial point of friction. Much time and energy by many parties has been spent over months debating and analyzing it.

Why not just implement a title history feature? Mods can change title, then users can click a link to show title history.

For extra points, you could make the title history page a poll/voting system which allows users above n karma, registered for x months to vote on their preferred title. Top voted title after y votes and z time after initial title change is what's used.

I definitely like the option of a title history + voting on which you believe is a "better" title. I also agree that limiting it to a certain threshold of karma, account age, etc, is appropriate.

I think having the original title as an option to be shown inside the comments would be nice.

Interesting to see these comments about transparency suddenly (after an entire 12 hour period) slide waaaaay down the page... I think this is the very [lack of] transparency we are talking about!

> I'd really like to see more transparency when it comes to title changes

So would I. Last time I mentioned this I got my head bit off (that's how it's always been!!). I don't care. It could AND SHOULD be better and WILL be if we demand it.

> I'd really like to see more transparency

I agree. From the random weighting down of certain articles, to title changes, to just flat-out removing/flaging some posts... it seems HN is becoming a "whatever the Mod who happens to be on today feels like" site -- which really detracts from the awesomeness of HN -- I'm not looking for a gatekeeper news site - if I wanted that, I'd go to CNN or something.

You're saying mods are responsible for some things that are user actions.

If dang is concerned about the noise being caused by users complaining about the effect of certain actions (either by mods or users,) that could probably be cleared up in the UI. Something as simple as an asterisk or an automatically generated note mentioning whether a mod changed a title or user flags killed a story would possibly clear up confusion.

Although the logical outcome of this would be some kind of graph generated for each thread that plots upvotes, downvotes, mod actions, user edits etc. over time but that would be insane...

Some wikipedia editors found a new home. Sometimes, people in a position of power, need some reassuring of that position by exercising the power. Most of the time however, the strong ones don't need that reassurance.

I saw the earlier title of this post while flipping through HN on my phone, and I wanted to read the full article during my lunch break. Now here I am, I checked the front page and was very confused where the post I was interested in went, and why some post apparently describing Lidar is at the top.

I guess they're trying to keep the title to match the title of the link/article. But sometimes the article just has a bad title. This slideshow is a great read, but with a title that puts me to sleep.

I too have the same experience.

It's not possible to mentally queue up items to read throughout the day. All the titles will have changed by that point.

I had the same experience exactly.

Agreed - the original title, about a guy beating a LIDAR ticket, was much more descriptive than this headline, which effectively says "This article is about LIDAR".

It was the fact that the guy was Joshua Bloch which got me to read the presentation - and I'm totally glad I did! I would never have read it if it was just named "The Lowdown on Lidar"

So appeals to authority work really well on you..

BTW, your downvotes are an opportunity to reflect on why your comment was obviously wrong and counterproductive.

Yeah, I had to read a lot of slides wondering why it was repeating the same thing over and over before I realized he was trying to beat a ticket. It definitely isn't a general purpose tech primer like the new title makes it sound, it's just focused on covering an error situation that gives you a legal out.

He tells you it was about a ticket on the third slide.

FYI, the original title was "Josh Bloch Fights a LIDAR Speeding Ticket (with Science)". Whereas that title gave information about the intention and action of the author (fighting a ticket), the updated title is relatively bland and refers to LIDAR in general.

"Why do we revert to orginal titles" https://news.ycombinator.com/item?id=6572466

The question has been asked, and answered, very many times.

The guidelines have advice about threads like these: https://news.ycombinator.com/newsguidelines.html

"We don't do this because it's too inflexible. [...] In others the subtitle makes a better title. But the fact that a title field is editable doesn't make it comment."

The original title of the post wasn't a comment on the content, but rather somewhat of a subtitle, which provided a better description.

A few days ago I commented about how an HN title had made me expect that the Amazon 3D printing store was 3D printing as a service, which alas, it is not.

The mods changed the title, which in that case made it less misleading, but they didn't leave any comment to say what the old title was. My comment no longer made any sense, and because a few hours had passed, I couldn't edit it to add a footnote for confused readers (and plus, I couldn't remember the precise wording of the original title).

I can understand why the titles are sometimes changed and most of the time I think it's for the better (although this time I agree it was a bad choice). What I would like to see added is a changelog feature, so that whenever the mods change a title, a footnote appears directly below the summary, before comments, showing who changed the title, what it had been, and optionally the reason it was changed.

That doesn't seem like a genuine question.

As for your factual claim, the post has been sitting near the top of the front page for 16 hours now.

I would assume such changes come from a desire to be accurate. But accurate how? In what way? That depends on the purpose of the title.

As I see it, our differences of opinion on this topic stem largely from misunderstanding it. I think it's not at all clear what we're even talking about, so we wind up arguing about slightly different things and fail to come to a consensus.

I think that we need to really understand the purpose of these titles, and to also understand that different people mean different things by the word "title". In fact, I think we're talking about three distinct but related ideas: titles, names, and summaries.

A name is a word or phrase that identifies a thing. A name isn't necessarily descriptive and often has no more meaning than being a word or phrase denoting the thing it names. My name is Adam. That tells you very little about me. All you can do with that is to identify me.

A summary describes a thing. I am a software developer with a penchant for pedantry. That's a summary. It actually tells you something about my nature, which the name "Adam" does not.

A title is first and foremost a kind of name. Ideally, it's also a descriptive summary, though that's not required. As a name, the important thing is that it is as short and as unique as reasonable. That's more important that descriptiveness.

In my opinion, Hacker News links should not be titles, i.e. names, but rather short summaries. Using a title is fine, but only as long as it's also a good summary.

The point of the front page is to link to things that are new and fresh. Ideally, most people won't have seen most things, meaning few will be familiar with their names. A page of new names that nobody recognizes is pretty pointless. You might as well use randomly generated words for the links. Or numbers. Like item?id=8114336.

Instead of titles, I think links should be summaries. When they are summaries, they can provide some real information about the thing that is linked. That can be used to decide whether to invest time in clicking through. When a link is just a name, you have little information to base that decision on, so you have to click most of the links to know which are the interesting ones.

But, if all HN links are summaries, how will we know what to call the articles they link? Well, if the summary is interesting enough to want to talk about, you'll click the link and see the actual title. Names are unimportant on the HN front page. They only become useful in the comments, and by then you should have at least read the title of the article, if not the whole thing.

The original summary here was useful and information-packed without being too long: "Josh Bloch Fights a LIDAR Speeding Ticket (with Science)". I care that it's Josh Bloch. I care that he's using science, in court. I care that it's about LIDAR and not RADAR. The fact that it's Josh Bloch, and that he's using science to fight a ticket means he was probably wrongfully ticketed, implying weaknesses in LIDAR speed guns that I want to understand. I got all that from a good, short summary.

The new summary is just the title of the linked article, which in this case is mostly just a name: "The Lowdown on Lidar". So, it's about LIDAR generally? Or as opposed to RADAR? Given the use of "lowdown", it's probably it's about some stuff that isn't commonly known. Maybe. Or maybe it's a boring, entry-level article on range finding in general that happens to talk about LIDAR rather than RADAR or SONAR. The title tells me very little and is not helpful in deciding whether to click the link, though it is a good name that's short and easy to use when talking about the article. I enjoyed reading "The Lowdown on Lidar".

The most important and useful thing a main page link can do is to accurately and faithfully inform the reader about the contents of the link. Accurately naming the linked thing is neither important nor useful. That is especially not useful when the name given by the original author misrepresents the contents, as is sometimes the case.

Accuracy is important in general, but we must be clear about specifically which kind of accuracy matters most here.

On Reddit, people post short summaries as titles. It isn't a good idea. A boring title may not be descriptive, but it's prescriptive: it prevents tainting the conversation. People shouldn't go into an article with a mindset established by a summary written by a random user. That privilege should be reserved for the author.

Why not have mods vet the summaries, like they do with titles? Because it'd be way too much work to do that for all articles. Dozens make it to the frontpage each day. And then we'll run into situations where the mods haven't vetted a summary at night (because they're sleeping) so some linkbaity summary flairs up to the frontpage for no good reason. This is exactly what happens on Reddit, and it's the reason HN should maintain its current rule regarding titles.

Good content, not good titles, should define HN as a community.

But, HN titles are content. They are part of the conversation about the article. I agree that authors should be able to title and summarize their own work, but only in that work. They shouldn't be given any special control of the conversation about that work, which is what HN is.

I don't see the purpose of having mods vet all titles or summaries. I don't think titles need any special blessing by an elite caste of users. I don't think it's important that titles be in any way "official" or even neutral.

Perhaps I'm not concerned because I also don't see duplicate posts as being especially bad. Maybe they are a bit annoying sometimes, but there are worse problems in the world. Why not simply embrace duplicates and let the best title rise to the top? Certainly people occasionally post comments saying essentially the same thing. There, we just let the voting system do what it does and push the best version to the top. Why not do that with titles as well? The only problem I can see is that conversations may be fragmented -- but copy/paste is super easy. Links in comments are easy to create and to follow.

The only real need I see for moderators is to occasionally deal with a flagrantly abusive link. Even that is questionable.

I think people are smart. We're mostly adults here, and we aren't easily controlled with blatantly editorialized links. I don't see any danger that we need protection from.

What's your response to this? https://news.ycombinator.com/item?id=6572466

Ah, thank you. That's what I assumed the policy was, but I wasn't sure if it was implicit or explicit. Now I know.

I guess the point I'm attempting to argue is that this particular policy is suboptimal and should be changed. Of course, when a policy or consensus exists, we should follow it. When it's a bad policy, we should follow it until we change it or remove it. I think we should change this.

My position basically boils down to a worse-is-better argument. I think the desire to maximize accuracy with original titles actually harms the conversation more than inaccuracies and editorializing in information-packed summaries.

What matters to me in this case is the signal-to-noise ratio, not the absolute level of noise in the data. Original titles can be "cleaner" and less noisy, but they also have relatively little information, or signal. I would rather have twice the noise if it gives me three times the signal.

I even see the noise as useful in a way. It adds color. Even when a title is inaccurate, it's sometimes interesting to think about how or why it is inaccurate. A little mess never killed anybody, and can even keep us healthy. Ultimately, if I'm so busy I don't have enough time to be occasionally mislead by a click-bait title, then I don't really have time to spend on HN in the first place.

I think the right way to deal with inaccurate titles is either to simply ignore them, or maybe to downvote them and to upvote duplicate posts with better titles. But won't HN then turn into reddit? I don't think so.

See, I think we try to fix too many things with laws where we should instead use social pressure. The reason that Americans don't litter very much isn't that it's now a ticketable offense. It's that we have decided that litterers are idiots and everybody hates them. The reason many subreddits are cesspools isn't the lack of rules, it's that they're populated by people who haven't collectively figured out a better way to behave -- or who don't particularly value the benefits of that different behavior. Adding a new rule won't fix anything if people don't understand and accept the purpose behind the rule. And if they understand the purpose, they usually don't need the rule.

Someone could argue that HN is something of a cesspool because so many comment threads go off topic. Like this one. Some people despise that. In general, though, HN users generally seem to appreciate an off-topic conversation so long as it's adding value. What we don't approve of is comments that don't add value. But, we don't need rules for that. It's just our commonly accepted behavior. Other groups have different values, and that's ok.

Plenty of subreddits have rules about editorialising titles and introducing bias, and they work well depending on the community.

But I'd rather have the odd editorialised title slipping through, than a large collection of bland, meaningless and decontextualised link titles. The current situation makes HN titles far inferior.

The current situation makes HN titles far inferior.

Good. HN titles being inferior will attract fewer new users.

If that is your aim, why not just use random numbers for titles? Or make all titles identical? That would certainly bring down the number of users by decreasing the pleasure of using the site, and repel new users.

Mission accomplished?

There's no reason to unnecessarily harm a community. On the other hand, there are plenty of reasons to resist making a community more popular.

I saw the title and google link and thought it would be someone from Google talking about the LIDAR system they use in their self-driving cars. I'd actually just read an article that said they cost $70,000 each so I was thinking "Maybe they have a way to drastically reduce the price or are going to say why they can't".

It's extremely confusing to me how the mods still can't comprehend this.

Agreed ... the title mentioning a guy using LIDAR (and Science!) to dispute a traffic ticket is completely different from a title that says "here's how LIDAR works". I agree, some transparency, or at least a history of previous titles, would be helpful.

Hell, lots of times I'll load 10 HN threads in my browser, to read later ... and then later when I get to them I refresh to start with the latest comments, look at the headline, and think "Um? When did I click on this? And where's that thread about ___? I think I clicked on that before ..."

This isn't reddit where sensationalizing your submission titles is encouraged. Submitters on HN should not be abusing the submission title to gain a privileged place in the discussion (i.e. editorials at the top of the page, unable to be affected by voting in the comments).

If you have an opinion on a submission, submit a comment to it.

What was the previous title? The current one is the same as the name of the provided link.

If you don't like the title, blame the author. Mods, afaik, are just trying to follow the rule that the submission should reflect the title of the article.

The title I first saw was:

Josh Bloch Fights a LIDAR Speeding Ticket (with Science)

Which is much better than the currently edited version.

I submitted the link with the title you note for the following three reasons:

1. Josh Bloch is an author of particular interest to this community.

2. When I searched to see if the page had already been submitted, I noted that recent HN posts on LIDAR were on technical laser ranging (e.g. in mapping applications), not on speed enforcement.

3. I thought it was an article that would be of interest to HN readers, so I thought they would be well-served by an appealing link title which conveyed the content and tone of the presentation and invited a click.

I saw the title after it was changed and I definitely thought that this was going to be a technical article about LIDAR in its 3D mapping application.

From the guidelines:

> Please don't do things to make titles stand out, like using uppercase or exclamation points, or adding a parenthetical remark saying how great an article is. It's implicit in submitting something that you think it's important.


> Otherwise please use the original title, unless it is misleading or linkbait.

> Please don't do things to make titles stand out, like using uppercase or exclamation points, or adding a parenthetical remark saying how great an article is. It's implicit in submitting something that you think it's important.

The submitter didn't do this.

> Otherwise please use the original title, unless it is misleading or linkbait.

Guidelines != rules. Sometimes authors write poor headlines (this is a great example). The community benefits from headlines that are more descriptive of the article. Having mods change them back for consistency's sake harms HN more than it helps.

I'd rather be on a website that errs on the side of "no linkbait" than a website that allows too much linkbait.

I'd rather not be on a website that takes itself so seriously that people obsess over rules/guidelines. It seems like every popular post has this confusion and argument about changing titles.

The original title is, indeed, misleading. The article is not about LIDAR specifically, but about how LIDAR is (mis)used in speed enforcement. IMO, the title change was warranted.

I think at this point your beef is with PG himself, or whoever he had write those guidelines.

The thing the mods are trying to avoid is link baiting, and they tend to err on the side of "no exceptions". I prefer this, as any other option may lead to more unintentional bias, or worse.

I suppose that "Josh Bloch Fights a LIDAR Speeding Ticket (with Science)" is a bit more link bait-y than "The Lowdown on LIDAR". I would also argue that the former compactly explains the entire content of the article, much more so than the latter, especially given that the author claims no expertise on LIDAR.

Regardless, I still would have preferred the original title. Perhaps removing the reference to Josh Bloch (and, perhaps, the parenthetical "with science") could have been dropped to reduce its link baity-ness.

As an addendum, I clicked on the link and read the article after the title had been changed to match the article's title, so perhaps my stated preference, as an afterthought, is completely unfounded.


"The Lowdown on LIDAR (Josh Blochs presentation)" is 47 chars and would probably have been kept.

Your title is link-baity. "Beats speeding ticket" and "with science" are obvious link bait. I'm kind of surprised that you thought your replacements would stick.

How would a reader know that this has to do with speeding radar, and not LIDAR use in ranging / mapping?

And I think it's relevant that the content of the presentation is scientific/analytic, rather than related to using legal strategies to invalidate a speeding ticket, for example.

> Which is much better than the currently edited version.

Not in my opinion. The speeding ticket Mr. Bloch fights is a secondary point to the main purpose of the presentation.

I agree it was stupid of the author to not have realized his presentation to a captive audience would be linked to the public and made it a more compelling title for casual consumption

Alternate questions: Why do authors keep using generic and vague titles? Why do submitters keep submitting content with generic and vague titles?

A title for someone who is already reading your blog fulfills a different purpose to a title for someone on an aggregator.

Anything else is declared misleading linkbait.

The title has been changed to the title the original author used, which seems appropriate. I think HN's title modding is done to prevent rampant link baiting and other titling by 3rd parties, instead entrusting it with the original author

I think this policy makes a lot of sense--it's best to ban editorialization of headlines altogether as there's no good objective way for mods to differentiate bad editorialization (sensationalism, inaccuracy) from good editorialization (adding pertinent information, clarifying, and de-sensationalizing).

However, there is also a strong argument to be made that there are good articles with lame titles (such as this one) which would otherwise be glossed over without a title change. Maybe the best solution would be to add a summary field to submissions, restricted to an 80-character, purely factual synopsis of the article's contents. It could show up smaller, beneath the submission headline, like a subtitle.

This way, you gain the benefits of editorialization (providing pertinent info highlighting the article's appeal to HN readers) while minimizing most of the downsides (loss of info provided in the title, misconstruction of the author's intent).

No, it's not appropriate here as the title only mentions "LIDAR", which I'm sure most of us have no idea what it means and won't care enough to read about it, whereas the original title gave context and desire to find out more.

The title has been changed to the title the original author used, which seems appropriate.

Titles have a context (which the author considered when they chose it). That context doesn't exist when it sits enumerated on the HN front page, invalidating the canonical title argument.

For instance when the author of this piece shared this, they did so under their own twitter account (coupling it with a name), and the supporting commentary "I gave this talk at a CA traffic ticket defense attorney seminar. Comments appreciated.". If these two elements didn't exist, and it was just tossed onto some pile of titles, it would be ignored.

I write a blog about software development, particularly financial and database related matters. I have vague titles like "Dealing with Variance" that makes total sense in the context of my blog and its readership, but is completely meaningless title outside of it.

While I do think there has been good transparency about title changes (a mod usually comments), the whole "what the original author intended" argument is misled.

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